Here:




Another:



The rib disappears from view when you are sighting the gun! This isnt that tough. All you see is the bead above the outline of the receiver. Ive never seen a flat swamped rib, not sure how you would pull that off, but, that doesnt mean it hasnt happened. The rib on the pictured LC Smith guns isnt really swamped- you will see the stub rib when sighting.
The gun that started this off isnt, either. You will be able to see that rib when sighting.

The swamped rib was an attempt to get the shooter to focus on the bird, not a rib.

Best,
Ted